1. Field of the Invention
This invention relates to a wheel-lift device for lifting and carrying a wheel mounted to an axle of a vehicle. More specifically the present invention is directed toward a wheel-dolly having a lifting means for raising a damaged or immobilized wheel of an automobile, truck, or machine, then carrying that wheel over obstacles when pulled by a winch or tow chain, or carrying wheel mounted on vehicle on a road or street when vehicle is attached to and pulled by a tow truck.
2. Background of the Invention
A wheel-dolly designed for use in the towing and recovery industry must be able to operate in off-road conditions. The dolly must be capable of travel over low curbs, rocks, and other obstacles while carrying an immobile wheel that is mounted on a vehicle. The vehicle and the dolly must be able to be winched by a tow truck over such obstacles. The towing industry now lacks such a device. The object of the present invention is to fill that need.
Wheel-dollies can be defined by design and usage into four classes. Dollies may share basic shapes and lift mechanisms between these classes. Wheel-dollies are usually designed to perform a single function well. Few wheel-dollies can crossover for use between classes as defined below.
A first wheel-dolly class is used to remove and replace wheel assemblies and brakes on vehicles. It is probably the most widely used type of wheel-dolly. It is a shop tool for use with a dismounted wheel assembly and maneuverable by hand. In use the dolly's wheels roll transversely to the wheel it carries. This wheel-dolly class often shares a basic U-shaped frame but is otherwise not comparable to wheel-dollies that carry a vehicle wheel still affixed to vehicle.
A second wheel-dolly class is used in pairs or sets of four to move vehicles within a garage or shop. This dolly class supports each wheel affixed to vehicle on a plurality of casters allowing movement of a vehicle in any direction when maneuvered by hand on a hard surface. H. E. Maurer, Jr., U.S. Pat. No. 1,275,716, August 1918, provided a wheel-dolly on casters that, when used under each wheel, would elevate an automobile so that it could readily be rolled around in limited space, especially within garages. Many variations and improvements to this basic concept have been made over the decades.
A third wheel-dolly class is designed to carry an immobile wheel on a road or street. This dolly's wheels roll parallel with the wheel it carries. It is installed on wheel affixed to towed vehicle's trailing axle in conjunction with leading axle of vehicle being carried by a tow truck. A towing dolly carrying both wheels of trailing axle is more widely used than individual wheel dollies, although several wheel-dolly types in this class are regularly used.
A shop-built wheel-dolly used in Europe has a fixed U-shaped frame with four small wheels mounted on spindles at each end of dolly leg. It requires vehicle to be lifted by a jack for placement of wheel onto dolly from above. Its low cost and narrow profile is an advantage over a towing dolly but seems limited by low towing speeds. Saufelle, U.S. Pat. No. 6,106,214, August 2000, provides a dolly that lifts and carries a wheel affixed to a vehicle using lifting paddles as wheel chocks. This dolly uses an adjustable support pad fixed to a vertical post against the top of the tire. It works best with undamaged wheels and suspension.
A wheel-dolly that carries a wheel affixed to a vehicle and pulled over obstacles by a tow chain or a winch cable connected to a tow truck constitutes a fourth class. Rollers of this wheel-dolly rotate parallel with vehicle axles and vehicle can be skidded on these rollers for turning, avoiding dragging vehicle wheels. A wheel-dolly is secured to each immobile wheel as a roller skate, reducing possible damage to vehicle components from towing. Wheel-dolly provides an indirect connection for attaching winch cable to vehicle. It appears that no existing wheel-dolly is recommended for use with a winch or for off-road usage. The present invention is therefore in a class by itself.
The preferred embodiment of the present invention incorporates one or more cylindrical rollers on each of two axles to traverse obstacles while carrying a vehicle wheel. That wheel, affixed to vehicle, is carried between wheel supports that share parallel axles with rollers. Vehicle's weight is transferred directly to the ground through the shared axle. Tubular axles enable the use of any of several four-point anchor schemes to secure a vehicle wheel to wheel-dolly's U-shaped frame.
Coccaro, U.S. Pat. No. 4,690,605, September 1987, taught a wheel-dolly with casters using a wheel support comprising a partial arc for lifting and carrying a vehicle wheel. The present invention uses a similar wheel support, but operates differently. Coccaro, U.S. Pat. No. 4,854,803, August 1989, further incorporates rollers to support vehicle wheel instead of using the earlier wheel support. Coccaro's wheel dollies with casters thus incorporated major elements of the present invention in separate devices. Both differ from the present invention by using casters to transport vehicle wheel on hard surfaces. The present invention is new and unique by combining the use of rollers that can be towed over soft and irregular surfaces with wheel supports for carrying a vehicle wheel on the same axle. It is also unique because it can be dragged while loaded by winch cables.
The present wheel-dolly uses an integral mechanical or hydraulic jack incorporated within its telescoping side frame that shortens or lengthens distance between dolly axles. Vehicle wheel is raised by shortening dolly frame causing wheel supports to rotate upward lifting vehicle wheel between them. If vehicle wheel is free to rotate, a single wheel support will raise through its arc before the second wheel support moves. If wheel is not free to rotate, each wheel support rotates upward in a synchronized manner to approximately similar angles. Vehicle wheel remains centered between axles in either case. A combined rotation of less than thirty degrees is adequate for wheel supports to raise a vehicle wheel. Wheel-dolly can carry vehicle wheel locked at an angle to vehicle's direction of travel by incorporating striations on wheel support surface and by making necessary adjustments on chain or strap devices when securing wheel to wheel-dolly.
Wheel supports arc within upper inner quadrants formed by wheel-dolly's axles and frame. Rotation of wheel supports is limited by vertical and horizontal stops incorporated within ends of wheel-dolly frame.
A preferred scheme for selectively connecting wheel-dolly to vehicle chassis is for first chain to course freely through round or oval-shaped chain guides in wheel-dolly frame. First chain extends rearward, there looping through a chain slip hook connected to an anchor to vehicle chassis, then coursing forward to be secured in wheel-dolly's rear chain latch. Forward end of first chain loops loosely from front chain guide to front chain latch, providing a chain loop for connecting winch cable slip hook. This scheme allows lighter weight, more flexible chain to be looped while providing higher working load limits compared to a single heavier chain. Winch cable is connected by this scheme to both vehicle chassis and to wheel-dolly. Because chain freely passes through chain guides and slip hooks, all chain segments are loaded equally when pulled by a winch. Wheel-dolly attachment scheme provides a low line of draft for winching vehicle upward over obstacles.
A vehicle wheel is also secured to wheel-dolly using two-point or four-point attachment schemes. A two-point scheme connects vehicle to wheel-dolly at the inner ends of axles using a chain looping over vehicle axle and further coursing through dolly axles. Chain ends are joined using a chain binder. Four-point attachments are made to inner and outer ends of both wheel-dolly axles.
Tubular wheel-dolly axles are preferred for use with second chains to secure vehicle wheel to wheel-dolly. An all chain device for holding vehicle wheel adapts parts from a common tire chain. At least two cross links extend across top of vehicle wheel approximately sixty degrees apart. A shorter outer tire chain having a master link at each end drops over face of wheel near its center. Inner tire chain having longer ends drop behind wheel, then course outward through tubular dolly axles. Chains are fished through axles using a rigid heavy wire hook. Chains turn upward for attachment to master links near the center of outer face of wheel.
An alternative basket strap device helps avoid possible chain damage to vehicle. Device is comprised of two longer parallel straps passing across the wheel at approximately a sixty-degree arc near its top, a plurality of shorter straps connecting the parallel straps near their centers. One longer strap is secured ahead of center of wheel by a chain segment coursing outward through forward axle of wheel-dolly and made taut by an integral strap winch hooked to that chain segment. Second longer parallel strap is then secured to rear axle of wheel-dolly behind centerline of vehicle wheel.
A wheel-dolly with small diameter rollers might require axles having an inside diameter too small for a second chain to pass through. Hooks can replace chain segments of basket straps, engaging removable eyebolts easily installed into wheel-dolly's axles with the simplest of tools, while avoiding any fixed protuberance extending from wheel-dolly.
Vehicle manufacturers may require that only wheel restraints be used for attaching a wheel-dolly to vehicles having independent suspensions. If wheel-dolly is to be used exclusively with such vehicles, a keyhole strap hooking over button-type connectors installed within axle ends is a simpler but less versatile alternative to basket straps or chain devices used with tubular axles.
Wheel-dolly can be used singly, in pairs, or in sets of four to move a vehicle. A pair of wheel-dollies used under drive axle facilitates moving a vehicle with its transmission locked in park position onto a car carrier without skidding vehicle wheels and tires. Four wheel-dollies facilitate damage-free loading of a locked four-wheel drive vehicle onto a car-carrier without skidding any tires across roadway. A vehicle can be towed with wheels carried by wheel-dollies for some distance and can be especially useful for clearing a vehicle causing traffic blockage from a busy street.
Wheel-dollies of this type can be used in pairs to carry a vehicle on roads in place of axle dollies or other wheel-dollies of the third class that are built to transport immobile wheels on roads. The present wheel-dolly offers the advantage of functioning as a recovery dolly as well. Use, practice, and experience will determine the preferred size and composition of rollers and other components that work best for dual purpose wheel-dollies.
Many vehicles, including recreational vehicles, have weak extended frames that require they be lifted and carried only by its axle or wheels. If a rear axle bearing failed on such a vehicle, a low loading angle truck or trailer is more likely to be used for recovery than a wrecker. If the vehicle's frame angles to the ground behind the failed axle, any attempt to load it onto a trailer from the front or rear can cause the frame to bend because the slightest upward angle of the tilted truck or trailer causes vehicle frame to support substantial weight at its end. A preferred recovery method lifts the axle. A wheel-dolly is a cost effective alternative available for recovering and loading a vehicle with axle failure onto a low loading-angle truck or trailer.
A road version of wheel-dolly can carry an axle with bearing failure without using a trailer. It carries its load only inches high, much lower than it could be carried on any trailer. It simplifies loading. Oversize equipment that might be over legal height when transported on trailers might alternatively be transported legally using heavy-duty wheel-dollies. Tubular axles accommodate larger diameter bushings for recovery dollies or wheel bearings of a size comparable to those used in truck axles for roadway towing. Wheel-dolly can be adapted for carrying industrial, construction, and agricultural equipment wheels on highways. A plurality of pneumatic tires might be used instead of rollers on axles of wheel-dolly for towing large vehicles or equipment having tall wheels. Trailer brake assemblies of several designs appear adaptable for mounting and use with larger versions of wheel-dolly.
Wheel-dollies work best with rollers less than one half the radius of vehicle wheel it carries. Multiple rollers can be used on each wheel-dolly axle for carrying dual wheels or wide industrial or agricultural tires. Wheel-dolly accommodates different wheel sizes by sizing wheel-dolly frame length to wheel and adapting hardware used to secure vehicle wheel or axle to wheel-dolly.
The present invention differs from other wheel-dollies by incorporating attachment schemes to secure wheel-dolly to vehicle chassis, to vehicle wheel, and accommodate attachment of tow chains and winch cables. A strong, yet lightweight wheel-dolly is achieved by using axle for both rollers and wheel supports and by using secured vehicle wheel to brace and strengthen wheel-dolly axles. The simple, sturdy design of this wheel-dolly will lift and carry a damaged or immobile vehicle wheel over obstacles when pulled by a wrecker winch or tow chain.
Industry magazines and catalogs provide a guide for available equipment and current usage. A leading nationwide vendor of towing accessories is AW Direct of Berlin, Conn. Its website, www.awdirect.com, and its comprehensive catalogs advertise wheel-dollies and tire skates that are available to the towing industry. A copy of pages 142–143 of their catalog “T505, good through Sep. 16, 2005” is attached. The pages describe and illustrate “GoJaks®” models GJ-5000, GJ-5400, and GJ-6000, all wheel-dollies with casters, along with a user warning that the dollies should not be used as towing dollies. Also advertised and illustrated are Auto Positioning Dollies MH98A, B, and C. AW Gear Tire Skates, models TS-400, TS-420, and TS-440 are recommended for loading car carriers. Wreck Master Skates WM-1 and WM-3 are adaptable to flat or wide tires and to brake rotors on vehicles without wheels.
Another page (138) describes Collins-Pacific Inc self-loading towing dollies, Models CD-20A, B, C, and D, and CD-25A, B, C, and D, that carry an axle of a vehicle and might be used by towing operators as a recovery dolly. Such usage is not mentioned in accompanying text and dollies are probably not recommended or designed for off-road recovery.